Advanced Settings of FXS Extension

This topic describes the advanced settings of an FXS extension.

Note: The FXS configurations require professional knowledge. Incorrect configurations may cause calling issues on the FXS extension.

VoIP settings

If you enable Linkus clients for an FXS extension, you may need to configure the following settings:

Table 1.
Setting Description
DTMF Mode Set the mode for sending DTMF tones.
  • RFC4733 (RFC2833): DTMF will be carried in the RTP stream in different RTP packets.
  • Info: DTMF will be carried in the SIP info messages.
  • Inband: DTMF will be carried in the audio signal.
  • Auto: If the device supports RFC4733 (RFC2833), PBX will choose RFC4733 (RFC2833), otherwise the PBX will choose Inband.
Transport Set the transport protocol.
  • UDP
  • TCP
  • TLS
Note: If you change the transport protocol, you must re-register the extension.
Qualify Enable this option to send SIP OPTION packet to SIP device to check if the device is up.
T.38 Support Enable or disable T.38 fax for the extension.
Note: Enabling T.38 will add performance cost. We recommend that you disable T.38.
NAT Enable this option when the PBX uses a public IP address. The feature is enabled by default.
Note: If you manually set up Linkus server, make sure the desired extension's NAT is enabled, or the extension user can not access Linkus when he or she is out of local network.
SRTP Enable SRTP for voice encryption.

Hotline

Hotline feature allows a phone to automatically dial a pre-configured number when the user goes off hook and a specific time interval passes.

Table 2.
Setting Description
Hotline Turn on the option to enable hotline feature.
Hotline Number Enter the hotline number.
Note: Only numbers, space, and ().- + * # are allowed.
Delay Dial (s) Enter the waiting time (in seconds) before automatically dialing out the hotline number.
Note: Only numbers are allowed.

Flash Detection

Set an amount of time to help the PBX identify if a hook flash is a valid event.

Table 3.
Setting Description
Min Flash Detection (ms) Set the minimum amount of time. The default value is 300.

To change the value, select a value from the drop-down list.

Valid values: 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000

Max Flash Detection (ms) Set the maximum amount of time. The default value is 1000.

To change the value, select a value from the drop-down list.

Valid values: 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000

Volume Settings

Set the transmitted and received volume of PBX.

Table 4.
Setting Description
RX Volume Set the volume from the analog phone to the PBX's FXS port. The default value is 40%.

To change the value, select a value from the drop-down list.

Valid values: 5%, 10%, 20%, 40%, 60%, 80%, 100%, 150%, Custom
Note: If you choose Custom, you must go to RX Gain (db) field to enter an integer between -30 and 12.
TX Volume Set the volume from the PBX's FXS port to the analog phone. The default value is 40%.

To change the value, select a value from the drop-down list.

Valid values: 5%, 10%, 20%, 40%, 60%, 80%, 100%, 150%, Custom
Note: If you choose Custom, you must go to TX Gain (db) field to enter an integer between -30 and 12.

Options

Table 5.
Setting Description
Call Waiting When receiving an incoming call during an active call, the user can hear a weak beeping sound that informs the user of the new incoming call. The user can press FLASH key on the analog phone to toggle between incoming call and the current call.
DTMF Passthrough

If this option is enabled, PBX will not process the DTMF tones, and pass DTMF tones transparently to the other end.

Echo Cancellation If this option is enabled, PBX removes extra noise and improves sound quality during a call.